Monday, February 17, 2014

Fossils and Behaviors

Sub-adult American alligator 
in Pearl River Delta, Mississippi. 
Photo by Kristine Gingras 
from the journal artlcle.
Crocodiles can climb trees.  "If crocodiles were extinct and you only knew them from fossils, you wouldn't be able to guess they climb trees because they don't have any physical adaptations," University of Tennessee researcher Vladimir Dinets told Reuters. "Assumptions based on fossils," he said, "can be far less correct than people think."
The article "Climbing behaviour in extant crocodilians" by Vladimir Dinets, Adam Britton, and Matthew Shirley appeared in Herpetology Notes (Vol 7:3-7; 2013), an online journal of Societas Europaea Herpetologica. 
"Extant crocodilians are generally considered to be predominantly or semi-aquatic. And, although the role of terrestrial activity in their natural history is increasingly recognized (see, for example, an overview of terrestrial hunting in crocodilians in Dinets, 2011), they are virtually never thought of as animals capable of climbing. Their non-arboreality is often taken for granted in various analyses of tetrapod limb evolution and behaviour of extinct Archosauria (see Birn, Jeffery et al., 2012, for a discussion of the subject and a bibliography)."
Reuters news story here.  
The article and the news story both state that this is not a discovery.  Crocodiles have been reported in trees by locals as well as by scientists in the field. The authors gleaned much of their data by convenience, surfing the Web for pictures. The climbers are overwhelmingly juveniles because they have high ratios of strength to body weight: strong claws and limbs; not much to lift. Fearsome as they appear and can be - death by crocodile is a reality for rural women in Africa - like most animals, they avoid conflict, dropping into the water to escape humans in boats who come within ten feet (three meters) or so.  The thesis of the article is that we admit some ignorance before speculating on the behaviors of dinosaurs.
Note that the primary investigator, Vladimir Dinets, has a broad range of interests (Wikipedia here; his own blog here).  He completed his doctorate at the University of Miami in 2011 studying crocodile behaviors, including coordinated hunting, and the use of tools. His publication in an online journal (with an essentially non-academic co-worker) also marks a kind of evolution.  The traditional peer review process of print journals has always been a trade-off between the screening out of crackpots and the exclusion of originality. Also, the long lead times were acceptable in the steam age.  Cyberspace is a new environment. We can share more, faster.  Of course, survival of the fittest in science still depends on empirical validation and falsifiable testing of rationally consistent claims. More subtly, we may well be living in a Renaissance time of broad personal achievements.  Scientists take cameo roles on television shows; and Hollywood actors have degrees in science. The co-authors of the article cited here footnote their marketing interests beyond the university. 

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